Troubleshooting, maintenance, and related administration to support customer's service level agreements (SLA) are a large part of an Optical Fiber Network Operator's operational expenses (OpEx) for optical fiber networks. The labor and material costs for troubleshooting and diagnosing maintenance or service outage problems within an optical fiber network can dominate an Operator's operating budgets and impact customer's SLAB negatively. Operators have deployed redundant networks that have multiple optical fiber links with automatic loss of link detection and switchover capabilities to insure SLAs and other mission critical services are maintained.
Usually when optical fibers are first deployed, highly skilled personnel or technicians with expensive fiber test equipment are assigned the task of ensuring and verifying desired optical fiber plant link budgets are met. This process of fiber plant deployment occurs before service is enabled to customers or during out-of-service periods, which are closely monitored and sometimes restricted due to customer's SLA constraints. All Long Haul, Metro and Access optical fiber networks are similarly deployed in this manner.
Once a customer or subscriber service is enabled, Operators are responsible for the troubleshooting, maintenance and servicing required by the optical fiber links as they degrade over time. This places extra cost burden on the fiber plants to provide field testability. Typically this field testability requires extra splitters at ends of optical fiber links to allow the connection of optical test equipment. Each additional splitter not only means more capital expense (CapEx) is incurred by the Operator but it also takes away precious dBs from the optical link budget. Operators greatly value their fiber plant optical link budgets where reach and other optical link margin related policies are used to differentiate its service offerings at an optical fiber link level. Operators thus use non-network affecting optical test methods like Optical Time Domain Reflectometry (OTDR) using specialized hand-held devices which use maintenance wavelengths, or optical supervision channels, such as 1625 nm wavelength that is separate and independent from all other wavelengths used to carry customer service network data communications. This is a capital and labor intensive method for routine fiber maintenance checks while ensuring service outages do not occur.
Therefore performing optical fiber network certification or a troubleshooting procedure or maintenance procedure without the requirement for manual troubleshooting, additional maintenance splitters, and without the requirement for a separate and dedicated maintenance wavelength is highly desirable to Operators due to realized OpEx, CapEx and optical link budget savings.